rec-apply4

Test of use of functions as arguments to other operators.

W3C sample	WIRIS
	$(\tan -\cos )(x)$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <apply>
      <minus/>
      <tan/>
      <cos/>
    </apply>
    <ci>x</ci>
  </apply>
</math>

Author: Design Science, Inc (D. Doyle, R. Miner)